1. Field of the Invention
This invention generally relates to design and simulation of integrated circuits and more specifically relates to simulation of domino logic circuits for use in integrated circuits.
2. Description of the Related Art
Domino circuitry is a well recognized branch of digital logic circuitry. However, due to its dynamic nature, it is inherently susceptible to noise in a way that static circuitry, the other well recognized branch of digital logic circuitry, is less susceptible. Domino circuitry tends to propagate noise, rather than damping out noise as static circuitry tends to. As a result, simulating domino circuitry to determine whether it is susceptible to noise either generated within the circuit or received from prior stages or surrounding circuitry is of great importance.
Integrated circuits utilizing domino circuitry are becoming more and more complex. Transistor minimum geometries are shrinking, the dies upon which these transistors exist are increasing in size, and therefore the number of circuits that can be placed on an integrated circuit is increasing. As a result of these increases more highly interconnected domino circuitry is included in each complex digital integrated circuit.
Furthermore, more opportunities exist for some form of crosstalk or other noise inducing phenomenon. Crosstalk typically occurs when two conductors are located close to each other physically. These two conductors are typically not actually connected or otherwise coupled together intentionally by a designer. However, some form of coupling occurs as a result of which a change of the voltage on a first conductor such as the transition from a high-to-low or low-to-high logic state will result in some form of noisy transition or change in logic state of a second conductor. This transition or change on the second conductor, which is not caused by whatever logic is driving the second conductor, results in noise which may be propagated through any domino circuitry coupled directly to the second conductor. Once propagated through that domino circuitry it may be propagated through further stages of domino circuitry. As a result it is of great importance that domino circuitry be simulated both in terms of its susceptibility to noise but also in terms of how the physical layout of the domino circuitry and its incoming and outgoing conductors tends to lead to noise being injected into the circuitry.
Classically, each stage of a circuit has been simulated independently, therefore a designer would have to design a simulation for each stage of his or her circuit and then in some manner determine what the worst-case results of preceding stages were in order to simulate the noise characteristics of whichever stage the designer is focusing on at that time. As circuits get more and more complicated and as designers are responsible for larger and larger portions of circuitry, this approach becomes inherently unwieldy, to the point where a designer may be expected to spend significantly more time simulating the circuitry than could possibly be allowed for in today""s rapid-paced and tight schedules.
In one embodiment, the invention is a method. The method includes extracting parameters of a set of domino logic circuits. The method also includes simulating each domino logic circuit of the set of domino logic circuits. Also, the method includes reporting results of the simulation.